1. Field of the Invention
The present invention relates to a backlight of a liquid crystal display device, and particularly to a backlight applying transmissive light to a transmission-type liquid crystal panel provided in a liquid crystal display device.
2. Description of the Background Art
Conventionally, a cold-cathode tube and a light-emitting diode (LED) have been used as a light emitting source of the backlight for a liquid crystal television set. As an example of the backlight using an LED, a plurality of LEDs are arranged in a plurality of rows and columns on the backside of the liquid crystal panel and are sequentially lit on a time division basis (for example, see Japanese Patent Laying-Open No. 62-234133).
Furthermore, as another example of a backlight using an LED, an edge-light type light guide plate is provided on the backside of the liquid crystal panel, in which a plurality of LEDs are arranged on the end face of the light guide plate to apply the light of each of the plurality of LEDs through the entire surface of the light guide plate to the liquid crystal panel (for example, Japanese Patent Laying-Open Nos. 2005-283829 and 2008-010291).
However, in the conventional backlight using a cold-cathode tube, for example, even in the case where only a part of the image is bright while the remaining part thereof is dark, the entire liquid crystal panel needs to be uniformly illuminated, which poses a problem that the power is wasted.
Furthermore, the conventional backlight using a plurality of LEDs arranged in a plurality of rows and columns requires a large number of LEDs and wiring arrangements. This poses a problem that the device configuration increases in complexity.
Furthermore, in the conventional backlight using an edge-light type light guide plate and a plurality of LEDs, the entire liquid crystal panel needs to be uniformly illuminated as with the conventional backlight using a cold-cathode tube. This also poses a problem that the power is wasted.